Abstract

Twin-screw extrusion is a powerful solution for biorefinery of sunflower whole plant. Thermo-mechanical fractionation and aqueous extraction are conducted simultaneously. A filter is outfitted along the barrel to collect a filtrate and a cake meal. Best oil yield is 57%. Proteins are also partly extracted, just as pectins. The cake meal is relatively moist (63%), and it is first dried. It is largely composed of fibers (58%). Oil content is 14% (40% of oil in whole plant). Protein content is 7% (51% of proteins in whole plant). As a mixture of fibers and proteins, this natural composite is successfully processed into biodegradable agromaterials by thermo-pressing. During moulding, macromolecular structure of proteins is transformed. Effects of pressure and temperature result in their glass transition. Proteins ensure the agromaterial cohesion. Fibers entanglement also acts like reinforcement. Stress at break and elastic modulus increase with temperature, pressure and time chosen for thermo-pressing. Highest flexural strength at break and highest elastic modulus are 11.5 MPa and 2.2 GPa. Density is then 1.04, and the corresponding panel is also the most resistant to water. Because of its promising mechanical properties, it would be usable as inter-layer sheet for pallets or for the manufacturing of containers.